Wildwater Kingdom, a $10.5 million amusement park in Allentown, Pa., opened its doors June 15, less than two months after Gov. Richard L. Thornburgh declared a drought emergency for Allentown and much of eastern Pennsylvania.

Sixteen counties in eastern Pennsylvania, New York City and much of New Jersey are now struggling with a drought that officials do not expect to abate for many months.

But at Wildwater Kingdom, there is a wave pool the size of a football field, three 10-foot-deep swimming pools, five water slides ranging up to 340 feet long, and a nine-level inner-tube ride.

Although the park dug its own well, recycles much of its water and has cut down the number of attractions because of the water shortage, still "people see the water, and it's hard to explain," said Kathy Kanish, public relations manager.

Water rationing and bans on such nonessential uses as watering lawns, washing cars and filling pools are in effect throughout much of the region. In New York, businesses have been ordered to cut water consumption by 20 percent, while industries in northern New Jersey must reduce their water use by 25 percent.

The problem is a lack of rain that started last August, said Thomas O'Connell, chief of strategic services for New York City's Bureau of Water Supply. Since then, the city's upstate reservoirs have collected 14 inches less rain than normal. Fourteen inches is about four months' worth of rain.

"We have no way of knowing how long it will last," O'Connell said. "We have to lay out a plan to meet the needs of the city in the event we face" a drought as bad as the worst on record, which occurred between 1964 and 1966.

Indeed, "the situation is grave enough" that city officials are considering pumping water from the Hudson River just south of Poughkeepsie, an emergency measure used only during the drought of the mid-1960s, said William Andrews, spokesman for the city's environmental protection department.

And, in anticipation of the dog days of July, the city plans to lock one-third of its 100,000 fire hydrants. "We exhausted the supply of hydrant locks in the country," said Andrews of the attempt to use locks to stop a traditional way of cooling off in the city.

One of the key uses of water being cut back is the use of air conditioners, which consume as much as 90 million gallons on scorching summer days, O'Connell said. And businesses have been ordered to cut their use by two hours each day. "Most of the buildings here are glass boxes, and no windows open," he said. "There have been some mornings it's been pretty sticky."

He said other tactics to cut water use include stopping leaks and reusing water rather than sending it down a drain.

Much of the drought is occurring in the region known as the Delaware River Basin, which affects the water supplies for about 7 million people, said John Rattie, water resources engineer for the Delaware River Basin Commission, a multistate governing body for the river's resources.

"The average person is not really feeling it just yet, but the potential for having serious problems this fall is very good," Rattie said. The problem is threefold: The reservoirs in the region that collect surface water are down because of low rainfall. New York City and northern New Jersey reservoirs were less than 60 percent full in April when they should have been almost brimming over, according to water officials. Lack of rain has also depleted groundwater supplies. Southern and coastal areas of New Jersey and the suburbs of Philadelphia get their water from wells and aquifers. The flow of the Delaware River is greatly reduced by the lack of rain. Salty water from the Atlantic has begun creeping up the river. If the salt level continues to move up the river, it could threaten drinking water for several million people in the Philadelphia area, said Bruce Dallas, spokesman for Pennsylvania's Department of Environmental Resources.

The water restrictions in Pennsylvania are livable and are designed to minimize problems for businesses, Dallas said. Golf courses can water the greens and tees but not fairways, he said. And commercial car washes are permitted to operate, even though residents can't wash their cars at home.

To encourage conservation, northern New Jersey residents are being charged at least $5 more for water if they use more than 50 gallons per person per day and businesses are paying a 33 percent water surcharge, said John Gaston, water resources director for New Jersey's environmental protection department.

So far, "at least 100 summonses and 500 warnings" have been issued to residents caught washing cars or watering lawns, Gaston said.

"It would take a return to normal rainfall for many months before you begin to see a positive change," O'Connell said.

And then there is the problem of keeping people from returning to their wasteful water ways when the rain starts falling. "People are lulled into thinking the drought is over because of rain," said Rattie. "Everybody sees their tomatoes growing and they say, 'What drought?' "